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Biomedical subjects

H Oelert

Publications and source records attributed to H Oelert.

At least 91 records · Page 5Linked to original sources
PubMed1996

[Intravascular therapy of aortic aneurysms: initial clinical results].

PURPOSE: A clinical study aiming at examining the implantation technique and the clinical results of a new vascular prosthesis in endovascular therapy of aneurysms of the aorta. MATERIAL AND METHODS: In 21 patients (20 men of 55 to 87 years of age, average age 70 years) with aneurysms of the infrarenal abdominal aorta (AAA n = 19) and the thoracic aorta (n = 2), a self-expanding nitinol stent with outer Dacron sheath (tubular prosthesis n = 4; bifurcation prosthesis n = 17) was implanted by means of an F-18 introductory set after surgical opening of the inguinal artery. RESULTS: By means of the 4 tubular prostheses and 13 of the 17 bifurcation prostheses the aneurysm was bypassed completely. In 4 cases residual perfusion through leaks (n = 3) or collateral blood supply (n = 1) was seen. In 6 patients 7 complications occurred which did not require to be operated on. No patient died in consequence of the surgical intervention or during the hospital stay. Follow-ups up to 8 months after surgery did not reveal any late complications to date. CONCLUSIONS: Endovascular implantation of vascular prostheses is a promising new method for interdisciplinary treatment of aneurysms of the aorta.

Aged↗
PubMed1996

Acetylcholine in isolated airways of rat, guinea pig, and human: species differences in role of airway mucosa.

Stored endogenous acetylcholine (ACh) and in vitro synthesis of [3H]ACh were measured in isolated, mucosa-intact and mucosa-denuded airways of rat, guinea pig, and humans. In addition, choline acetyltransferase (ChAT) activity and ACh content were measured in freshly isolated airway mucosa as well as in cultured epithelial cells of rat tracheas. Rat tracheas stored 25 nmol/g ACh, whereas guinea pig tracheas and human bronchi contained only 2-3 nmol/g ACh. When incubated with [3H]choline, the isolated airways of rat, guinea pig, and human synthesized significant amounts of [3H]ACh. In guinea pig and human airways, removal of the mucosa affected neither stored ACh nor in vitro synthesis of [3H]ACh. In rat tracheas, however, removal of the mucosa resulted in a 50% reduction of stored ACh. Freshly isolated mucosa wiped off from the luminal surface of rat tracheas contained large amounts of ACh (6.5 nmol/g airway), whereas in human mucosa (central bronchi) only small amounts of ACh were found. In enzymatically isolated mucosal cells of rat tracheas, a considerable ChAT activity (21 nmol.mg protein 1.h-1) was detected, blockable by bromoacetylcholine. Enzymatically isolated human mucosa contained a rather low ChAT-like activity (0.5 nmol.mg protein 1.h-1), not sensitive to bromoacetylcholine. In cultured epithelial cells of rat tracheas (4th-6th passage), neither ChAT activity nor ACh was detected. The large airways of rat, guinea pig, and humans contain considerable amounts of ACh, supporting histological evidence of a dense cholinergic innervation, particularly of rat tracheas. The mucosa of rat tracheas synthesizes and stores large amounts of ACh, whereas the low ChAT activity in human mucosa argues against the presence of cholinergic neurons able to synthesize and store ACh.

Acetylcholine↗
PubMed1996

Cystic medical necrosis of the internal thoracic artery.

In an internal thoracic artery intended as a graft in coronary angioplasty, multiple intramural haematomas impeded blood flow and consequently precluded use of the artery as a free graft. The cause was found to be cystic medical necrosis of the internal thoracic artery. A good result was obtained with three single aorto-coronary venous bypass grafts.

Coronary Artery Bypass↗
PubMed1996

Effects of surface seeding with vital cells on the calcium uptake of biological materials for heart valve replacement.

BACKGROUND AND AIMS OF THE STUDY: Up to 35% of bioprosthetic heart valves need to be replaced during the first decade after implantation because of tissue degeneration or calcification. The aim of the studies was to evaluate the influence of surface seeding with viable cells on the calcium uptake of biomaterials. MATERIALS AND METHODS: Samples of glutaraldehyde tanned bovine pericardium (GBP, n = 52) or porcine valves (GPV, n = 50), or glycerol treated bovine pericardium (GlyBP, n = 35), which had either been rinsed with saline (GBP, n = 30; GPV, n = 26; GlyBP, n = 18) or seeded with rat fibrocytes (GBP, n = 22; GPV, n = 24; GlyBP, n = 17) were incubated with cell culture medium containing physiologic levels of calcium. Similarly treated material was implanted into the abdominal muscles of 88 rats (seeded: GBP, n = 16; GPV, n = 16; GlyBP, n = 14; non-seeded: GBP, n = 6; GPV, n = 8; GlyBP, n = 7). The specimens were analyzed two and four weeks later for their calcium content. RESULTS: Over time untreated GBP and GlyBP calcified in vitro and in vivo while GPV retained low calcium levels in vivo. Surface seeding with rat fibrocytes significantly reduced the calcium accumulation in GBP and GlyBP in vitro and in vivo (p < 0.05). CONCLUSIONS: Seeding with viable cells might be a promising method of reducing calcium accumulation in bovine pericardial implants.

Animals↗
PubMed1996

[Intravascular stents for treatment of systemic venous obstructions].

Two young adults, 16 and 18 years of age were admitted with complete occlusion of the superior vena cava pathway following previous Mustard procedure. In both patients, perforation of complete occluded vein segment using a straight guidewire and subsequent sequential enlargement by balloon dilation were successfully performed by a left subclavian vein approach. Implantation of a 30 mm Palmaz-stent resulted in a widely patent channel of the vena cava superior into the systemic venous atrium. In short-term follow-up of 3 months both stents remained patent. Repeat dilation of the stents was performed after 3 months. A third patient with systemic venous obstruction was a 3-year old child who suffered low cardiac output following modified Fontan operation caused by a narrowing of the superior vena cava to right pulmonary artery connection and stenosis of distal left pulmonary artery. The severe hemodynamic problem was resolved by implantation of Palmaz-stents in the two separate obstructions. At recatheterization 6 months later, both stents were patent without any residual pressure gradient.

Adolescent↗
PubMed1996

[Surgical closure of atrial septum defects via right-sided thoracotomy. Value with reference to the development of interventricular closure techniques].

Surgical closure of atrial septal defect is a safe and effective procedure with low morbidity and mortality. A right anterior thoracotomy approach is a suitable alternative to that through a median sternotomy and provides superior cosmetic results. Thirty patients at the age of 1 year, 3 months to 49 years underwent repair of atrial septal defects through a right thoracotomy. Twenty-four patients had secundum, three ostium primum, two sinus venosus defect, and one patient had Scimitar's syndrome. Details of the surgical procedure on cardiopulmonary bypass are presented. There was no operative or late mortality, and no morbidity directly related to the alternative approach. All patients or their parents considered the cosmetic result fair or satisfying. The following paper reflects our experience with the thoracotomy approach for repair of atrial septal defects, as well as a critical review of new developments in interventional ASD occlusion techniques.

Adolescent↗
PubMed1996

[Cardiosurgical stand-by and acute interventions after interventional cardiologic procedures].

Interventional cardiologists and cardiac surgeons agree in the treatment of symptomatic coronary artery stenosis: high risk patients with severe coronary disease (such as left main stem stenosis, triple vessel disease and double vessel disease with involvement of the proximal LAD in particular with severely impaired ventricular function) are treated preferentially with coronary artery bypass grafting (CABG); less severe cases allow alternatively PTCA treatment. However, even in controlled and randomised studies (RITA, GABI, ERACI, CABRI, and BARI-studies) looking into these alternatives (PTCA versus CABG) it was found that 1.1% to 10.1% of all PTCA incidents required a surgical emergency procedure. Although, in favourable conditions the risk is considerably lower than the above value and despite of improvement of catheter techniques (stent implantation, perfusion catheters) in less favourable conditions which reduced the risk to a similar value, the results of surgical emergency procedures are still significantly impaired compared with elective procedures. Moreover it has been shown that there is a relation between the outcome of the surgical procedure and the time elapsed between PTCA-incident and surgical intervention. Perioperative myocardial infarction and mortality are much lower if there is no delay caused by occupied theaters, unsolved transportation problems and/or time intensive attempts of recanalisation by catheter. Considering the high numbers of PTCA procedures, in some centers even performed simultaneously, it seems acceptable to perform a dilatation in the low risk group without surgical standby. If strict observance of the indication criteria is provided early complication rate and mortality of PTCA is even less than in CABG-procedures. On the other hand (from a cardiosurgical point of view), it has to be emphasized that PTCA procedures in the high risk group potentially endangering large myocardial areas, a cardiosurgical standby has to be available and emergency surgery should be performed ultimately within 60 minutes (after myocardial infarction).

Angioplasty, Balloon, Coronary↗
PubMed1995

[The perforation of a right-coronary sinus of Valsalva aneurysm into the right atrium].

HISTORY AND CLINICAL FINDINGS: A 58-year-old man [correction of woman] without previous cardiac symptoms developed exertional dyspnoea and peripheral oedema which markedly increased within a two-week period. Auscultation revealed a 4/6-5/6 holosystolic and diastolic machinery murmur. EXAMINATIONS: Transthoracic and multiplane transoesophageal echocardiography established the diagnosis of a 3 cm aneurysm of the right coronary sinus of Valsalva with clearly demarcated rupture into the right atrium, with a large left to right shunt shown on colour-Doppler echocardiography. These findings were confirmed on cardiac catheterisation. There was no sign of coronary heart disease. TREATMENT AND COURSE: At open-heart surgery the aneurysm was resected, the defect closed with an autologous pericardial patch and the tricuspid valve reconstructed. On follow-up examination the result remained excellent and the patient was free of symptoms. CONCLUSION: In ruptured aneurysm of the coronary sinus of Valsalva, multiplane transoesophageal echocardiography provides exact diagnosis and optimal planning of the operative procedure.

Aortic Rupture↗
PubMed1995

Transcatheter radiofrequency perforation and stent implantation for palliation of pulmonary atresia in a 3060-g infant.

In a 3060-g infant with fibromuscular pulmonary atresia an open right ventricular outflow tract was created by means of interventional cardiological methods. Following two inadvertent perforations without sequelae or clinical symptoms, radiofrequency perforation and subsequent balloon dilatation were successfully performed. The implantation of a Palmaz iliac stent led to a predictable communication between the right ventricle and pulmonary artery.

Cardiac Catheterization↗
PubMed1995

Relevance of immunologic reactions for tissue failure of bioprosthetic heart valves.

The use of biologic heart valve prostheses is decreasing because of the high incidence of failure of these bioprostheses resulting from tissue degeneration or tearing. Immunologic reactions might play a decisive role in this process. The present experimental and clinical studies were conducted to investigate the relevance of immunologic reactions to the tissue failure of glutaraldehydetanned bovine pericardial and porcine valves. Specimens of the two different types of valve material were implanted in the abdominal muscles of rats. Enzyme-linked immunosorbent assays and tritiated thymidine incorporation tests were performed to detect specific antibodies and activated T cells. All specimens were studied histologically. Identical enzyme-linked immunosorbent assays and tritiated thymidine incorporation tests were performed in 29 patients with bioimplants and in 48 controls. Twenty explanted bioprostheses were investigated using histologic and immune histologic methods. The results of the enzyme-linked immunosorbent assays and lymphocyte proliferation tests showed that glutaraldehyde-tanned bovine pericardial valves can provoke cellular and humoral immunologic reactions in rats and human beings. In explanted bovine valves, macrophages were found invading and degrading implant collagen, starting from surface lesions. The combination of the formation of mechanical lesions, the development of cellular infiltrates, and collagen disruption strongly indicates that initial surface lesions initiate the immunologic reactions in bovine pericardial valves as the result of the exposure of incompletely tanned collagen. These immune responses might accelerate tissue degeneration. Porcine valves do not provoke immunologic reactions.

Animals↗
PubMed1995

Age-dependent changes in the beta-adrenoceptor-G-protein(s)-adenylyl cyclase system in human right atrium.

With increasing age, cardiac beta-adrenoceptor function decreases. To study possible mechanisms underlying this process, we assessed in right atrial appendages from 52 patients of different ages (group A, < 20 years, mean age 3.7 +/- 1.0 years, n = 20; group B, 20-50 years, mean age, 37.9 +/- 2.3 years, n = 9; group C, > 50 years, mean age 66.1 +/- 1.5 years, n = 23) without apparent heart failure who were undergoing open heart surgery beta-adrenoceptor number and subtype distribution (by (-)-[125I]-iodocyanopindolol [ICYP] binding), adenylyl cyclase activity, and Gs- and Gi-protein alpha-subunits (by quantitative Western blotting). beta-Adrenoceptor number in the three groups was not significantly different; in contrast, basal, 10 microM GTP-, 100 microM isoprenaline (ISO), 10 mM NaF-, 100 microM forskolin-, and 10 mM Mn(2+)-stimulated adenylyl cyclase activity was significantly higher in group A than in group B and was further decreased in group C. Similarly, 100 microM terbutaline-, 100 microM histamine-, and 100 microM 5-HT-stimulated adenylyl cyclase activity significantly decreased from group A to group C. Moreover, all these adenylyl cyclase parameters were significantly negatively correlated with the age of the patients. Although Gs alpha was not altered, Gi alpha in group C was significantly higher than in group A; moreover, there was a weak but significant positive correlation between Gi alpha and the age of the patients. We conclude that an impairment of the activity of the catalytic unit of adenylyl cyclase is involved in the decrease in cardiac beta-adrenoceptor function with age; an increase in Gi alpha might contribute further to the reduced beta-adrenoceptor function.

Adenylyl Cyclases↗
PubMed1995

The ineffectiveness of the NO-cyclic GMP signaling pathway in the atrial myocardium.

1. This study was performed to determine whether nitric oxide (NO) has direct effects on force of contraction (Fc) in atrial myocardium from rats, rabbits, guinea-pigs, frogs, and man. 2. Glyceryl trinitrate, isosorbide dinitrate, 3-morpholino-sydnonimine hydrochloride (SIN-1), and S-nitroso-N-acetylpenicillamine (SNAP) did not significantly reduce Fc in the various preparations investigated, either given alone or after stimulation of alpha- or beta-adrenoceptors. 3. SNAP did not change the time course of contractions in rat, guinea-pig and human preparations. 4. 8-Bromo-guanosine-3':5'-cyclic monophosphate (8-Br-cyclic GMP) produced a negative inotropic effect in rat, guinea-pig and human atrial preparations and shortened time to peak tension and relaxation time in human preparations. 5. High K+ (85 mmol l-1)-induced contracture in rat heart muscle was reduced by 8-Br-cyclic GMP but not by SIN-1. 6. N-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthase, failed to influence muscarinic effects on Fc or frequency from rat and guinea-pig hearts. 7. We conclude that NO, under the experimental conditions described here, has no direct effects on the heart, although cyclic GMP may be involved in the regulation of myocardial contraction.

Acetylcholine↗
PubMed1995

Microscopic evaluation of an occluded intracoronary Palmaz-Schatz stent removed before coronary artery bypass grafting.

Intracoronary implantation of stent devices is a new interventional technique with a promising role in the treatment of acute coronary occlusions caused by intimal dissection and suboptimal results of percutaneous transluminal coronary angioplasty. However, the prolonged presence of stent material embedded in the arterial wall may generate unknown late consequences. Major complications consist of subacute to chronic occlusion and restenosis. To elucidate the underlying cause we removed an angiographically occluded intracoronary artery Palmaz-Schatz stent before coronary artery bypass grafting. Scanning electron microscopy showed thorough coating of the metal struts of the stent by normal neoendothelial cells. Side branches arising at the level of the stent were patent. According the specific angiographic feature thrombotic occlusion originated distally of the stent.

Aged↗
PubMed1994

Laser welding--suitable for vascular anastomosis?

Carotid arteries of 21 piglets were transsected and reanastomosed either by laser welding (Neodym:YAG laser) or by conventional suture anastomosis. Histological specimens of the anastomoses obtained 2 to 32 days after the operation showed less foreign body reaction and intimal hyperplasia after laser welding than after suturing. There was, however, no significant difference when comparing occurrence of thrombosis, patency rate, or growth of the anastomosis in growing animals. Neither our study nor a review of the literature of laser-assisted vascular anastomosis in microvessels and large arteries up to 5 mm diameter could establish a definite clinical application for laser welding in vascular anastomosis.

Anastomosis, Surgical↗
PubMed1994

[Transesophageal echocardiography in cardiogenic shock in acute posterior wall infarct with rupture of the papillary muscles].

A 63-year-old male patient suffered an acute myocardial infarction entirely confined to the posterior wall. As symptoms persisted and cardiogenic shock developed immediate heart catheterization was performed, which demonstrated an occlusion of the left circumflex branch. Right-heart catheterization demonstrated an enlarged v-wave. Thus, acute infarct associated mitral regurgitation was suspected. In the catheterization laboratory transesophageal echocardiography including Doppler- and contrast echocardiography was then performed, which revealed the diagnosis of posterior papillary muscle rupture. The patient proceeded immediately to emergency surgery during which mitral valve replacement with a St. Jude prothesis was performed in addition to venous bypass revascularization of the occluded and a further stenosed coronary artery. The postoperative follow-up was without any complications and the patient recovered satisfactorily from the acute event. This case demonstrates the excellent diagnostic utility of emergency transesophageal echocardiography in the situation of infarct related myocardial rupture, which has to precede the life-saving operation.

Cardiac Catheterization↗
PubMed1994

Enoximon-echocardiography. A new diagnostic approach for the detection of viable myocardium comparison to dobutamin-echocardiography.

UNLABELLED: Hypo- or akinetic myocardial regions can be identified as viable myocardium through recruitment of inotropic reserve. Both, dobutamine (D) as well as enoximone (E) mediate their inotropic action via an increase in intracellular c-AMP concentration based on a different action. In 10 patients with documented myocardial infarction either D (5 to 40 micrograms/kg/min, increments of 5 micrograms/kg/min every 3 min) or E (1 to 9 micrograms/kg/min, increments of 1 microgram/kg/min every 2 min) was administered intravenously on two consecutive days. Heart rate (HR), systolic and diastolic blood pressure (BP), as well as a wall motion score in 16 segment (WMS) and ejection fraction (EF) with 2D-echocardiography were determined at rest and during each increment. Viability of myocardial regions was assessed with 201thallium-SPECT (Table 1). RESULTS: *p < 0.05 vs. rest, data: mean +/- SD. While E did not cause any side effects, patients complained about rash (n = 10), headache (n = 8), angina pectoris (n = 5), and anxiety (n = 2) during the administration of D. D and E are both able to recruit a potential inotropic reserve in infarcted myocardium, and thus, identify viable myocardium. In contrast to E, D caused an increase in HR and systolic BP. Enoximone-echocardiography seems to be a new, promising tool for the identification of viable myocardium.

Adult↗